Careless storage? It's more than likely the dad and his son stored their weapons in the same safe/lockup, thus the access to it.[/quote]

Sounds like the son had his restricted but if he didnt and they shared a locker and the son had access to the hangun without one then yes the dad could be charged 100 percent, have seen it happen and actually go to court. You are responsible for securing your firearms from others easily accessing them.